Playing the very first mission in the campaign where you have to insert a spy into Japan. Keep getting attacked by planes almost as soon as I surface. Decide to only surface at night to recharge the batteries. But it doesn't get proper dark until 10:00pm. This is in early January too. Is that accurate for Japan area? It doesn't get fully light until around 11:00am either.

Seems off to me but I could be wrong.

If I remember right the USN actually used Zulu time and didn't compensate for different time zones so 10pm might be correct in January. I'm sure someone can clue us in on this.

Ah, that could be it, it is Zulu time. Thx.

Zulu time is UTC-0 and Japan is UTC-+9.